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Monodispered ZnO nanocrystals (NCs) were found to quench the fluorescence of two donor−π system–acceptor (D−π–A) dyes; (E)-2-cyano-3-[5-[4-(diethylamino)phenyl]thiophen-2-yl]-2-propenoic acid, 1, a...
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An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely... more
An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely... more
An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely... more
An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely... more
An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely... more
An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely... more
An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely... more
An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely... more
An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
R factor = 0.048; wR factor = 0.114; data-to-parameter ratio = 15.4. In the title compound, C13H10N2O4, the nitro groups are twisted significantly relative to the benzene rings [dihedral angles = 16.64 (18) and 28.02 (11)]. The benzene... more
R factor = 0.048; wR factor = 0.114; data-to-parameter ratio = 15.4. In the title compound, C13H10N2O4, the nitro groups are twisted significantly relative to the benzene rings [dihedral angles = 16.64 (18) and 28.02 (11)]. The benzene groups are nearly perpendicular to each other [dihedral angle = 87.72 (6)]. Short intermolecular N O and C O [2.981 (2) and 3.060 (2) Å, respectively] contacts suggest possible weak -interactions between nitro groups and between benzene and nitro groups. In addition, there are – interactions between one benzene group and an inversion-related equivalent [interplanar separation = 3.494 (2) Å]. Related literature The synthesis of the title compound has been previously reported (Allinger & Youngdale, 1962), although by different methods from the preparation of the sample used for this study [a modification of the method given by Lu et al. (2006)]. For related structures, see: Barnes et al. (1981); Brito et al. (2007); Cousson et al. (1993); Housty (1961).
Abstract Monoanionic mixed N2P2 donor beta-diketiminate (BDI) ligands with phosphine pendant arms, 2-(4-tolyl)-bis(2-diisopropylphosphinophenyl)propenediimine (abbreviated as Tol-BDI(DIPPP)2H), were prepared and metallated with zinc(II)... more
Abstract Monoanionic mixed N2P2 donor beta-diketiminate (BDI) ligands with phosphine pendant arms, 2-(4-tolyl)-bis(2-diisopropylphosphinophenyl)propenediimine (abbreviated as Tol-BDI(DIPPP)2H), were prepared and metallated with zinc(II) iodide. Three ligand variations have been synthesized by incorporating different substituents (methyl or methoxy) on the linker phenyl rings at positions 4 and 6. In the 4-methyl zinc complex [Tol-BDI(DIPPMeP)2ZnI] and 4-methoxy zinc complex [Tol-BDI(DIPPMeOP)2ZnI], the metal is bound to all four donors on the ligand, rendering a distorted square pyramidal geometry around the zinc metal with τ5 values of 0.25 and 0.29, respectively. However, the crystal structure of the 4,6-dimethyl zinc complex [Tol-BDI(DIPPMe2P)2ZnI] shows a four-coordinated zinc with only one phosphine bound to the metal, resulting in a distorted seesaw geometry around the metal. While X-ray crystallography shows no interactions between the metal center and the unbound phosphine, solution characterization reveals a symmetrical complex with both phosphines bound to the metal center in all three zinc complexes.
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Intra- and intermolecualr interactions play a strong role in the solid-state and solution electronic properties of d8 transition metal complexes. This is in part due to the steric availability of the dz2 orbital to interact with... more
Intra- and intermolecualr interactions play a strong role in the solid-state and solution electronic properties of d8 transition metal complexes. This is in part due to the steric availability of the dz2 orbital to interact with additional axial ligand donor/acceptor atoms or other d8 metal centers. Persistent interactions of d8 metals with atoms at distances and geometries that lie beyond covalent bonds but shorter than van der Waals radii can lead to interesting optical (both absorbance and luminescence), electrochemical, and NMR properties as well as unique reactivity. In our efforts to probe these types of weak interactions at d8 metals, we have observed unexpected gold (III) templated ligand chem. leading to spontaneous resolution of enantiomers, discovered multiple polymorphs in a platinum (II) system, each with unique photoluminescence properties, and studied a reversible temp.-induced single-crystal to single-crystal transformation in a palladium (II) complex accompanied by changes in color. The intra- and intermolecualr structural features of these d8 systems and their relationship to photophysical features will be discussed
Research Interests: Chemistry and Enantiomer
The preparation of halogenated benzene-1,2,3,4-tetracarboxylic diimide derivatives is challenging because of the possibility of competitive incorrect cyclizations and SNAr reactivity. Here, we demonstrate that the direct reaction of... more
The preparation of halogenated benzene-1,2,3,4-tetracarboxylic diimide derivatives is challenging because of the possibility of competitive incorrect cyclizations and SNAr reactivity. Here, we demonstrate that the direct reaction of benzene-1,2,3,4-tetracarboxylic acids with primary amines in acetic acid solvent successfully provides a range of desirable ortho-diimide products in good yields. Furthermore, we demonstrate that sterically challenging N-derivatizations can be readily achieved under microwave reactor conditions, and that SNAr reactivity is only observed when excess amine is used. The halogenated diimides described here are attractive building blocks for organic materials chemistry.
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A metal/ligand cooperative approach to reduction of small molecules by metal silylene complexes (R2Si=M) is demonstrated, whereby silicon activates the incoming substrate and mediates net two-electron transformations via one-electron... more
A metal/ligand cooperative approach to reduction of small molecules by metal silylene complexes (R2Si=M) is demonstrated, whereby silicon activates the incoming substrate and mediates net two-electron transformations via one-electron redox processes at two metal centers. An appropriately tuned cationic pincer cobalt(I) complex featuring a central silylene donor reacts with CO2 to afford a bimetallic siloxane featuring two Co(II) centers with liberation of CO, and reaction with ethylene yields a similar bimetallic complex with an ethylene bridge. Experimental and computational studies suggest a plausible mechanism proceeding via [2+2]-cycloaddition to the silylene complex that is quite sensitive to steric environment. The Co(II)/Co(II) products are further reactive to oxidation and reduction. Taken together, these findings demonstrate a strategy for metal/ligand cooperative small-molecule activation that is well-suited to 3d metals.
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Sandwich coordination complexes, [LnIII(H3L)2]X3∙solvents, of Tb(III), Eu(III), Dy(III), Ho(III) and Er(III) were prepared with two new zwitterionic ester-substituted tripodal amine ligands, tris((2-hydroxy-5-n-butyl... more
Sandwich coordination complexes, [LnIII(H3L)2]X3∙solvents, of Tb(III), Eu(III), Dy(III), Ho(III) and Er(III) were prepared with two new zwitterionic ester-substituted tripodal amine ligands, tris((2-hydroxy-5-n-butyl benzoate)aminoethyl)-amine (H3L1) and tris((2-hydroxy-5-methyl benzoate)aminoethyl)-amine (H3L2). These ligands were synthesised by condensation of the appropriately substituted salicylaldehyde with tris(2-aminoethyl)amine (tren) followed by in situ reduction of the tris-imine to tris-amine. Subsequent 2:1 reaction with lanthanide(III) ions yields [LnIII(H3L)2]X3∙solvents (L = L1, L2; X = Cl−, NO3−; solvents = MeOH or H2O). All complexes were characterised by microanalysis, infrared spectroscopy, high resolution mass spectrometry and solid-state photoluminescence measurements. The crystal structures of [TbIII(H3L1)2]Cl3·6MeOH, [Dy(H3L1)2]Cl3·6MeOH, [EuIII(H3L1)2]Cl3·6MeOH and [TbIII(H3L1)2](NO3)3 reveal high-crystallographic −3 symmetry at the O6-coordinated octahedral lanthanide(III) ions and that the tripodal ligands are bound in zwitterionic form: the protons from the phenolic oxygens have migrated to the amino nitrogens. Photoluminescence measurements indicate various degrees of energy transfer of the ligand chromophore to the lanthanide ions, as both ligand and lanthanide emission features are observed. Despite the high-crystallographic symmetry and the likely small transverse magnetic anisotropy of the complexes, no evidence of slow relaxation of the magnetisation, characteristic of a single-molecule magnet, was observed for [TbIII(H3L1)2]Cl3·MeOH·3H2O, [DyIII(H3L1)2]Cl3·6H2O, [HoIII(H3L1)2](NO3)3·2H2O, [ErIII(H3L1)2]·H2O and [TbIII(H3L1)2](NO3)3 down to 2.0 K.
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A trithiamacrocyclic ligand complex of Au(iii) undergoes a redox-mediated thermal reaction to form a chiral bicyclic sulfonium salt.
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The synthesis and characterization of a series of cyclometallated complexes of Pd(II) incorporating the mixed donor ligand 1-oxa-4,7-dithiacyclononane ([9]aneS2O) are presented in this study. Complexes of the form [Pd(C^N)([9]aneS2O](PF6)... more
The synthesis and characterization of a series of cyclometallated complexes of Pd(II) incorporating the mixed donor ligand 1-oxa-4,7-dithiacyclononane ([9]aneS2O) are presented in this study. Complexes of the form [Pd(C^N)([9]aneS2O](PF6) (C^N...
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The title salt, NH4+·H+·2C14H9N4O2−, is composed of an ammonium cation with a strong intermolecular negatively charge-assisted hydrogen-bonded acid/conjugate base-pair monoanion. The carboxylic acid H atom is located on an inversion... more
The title salt, NH4+·H+·2C14H9N4O2−, is composed of an ammonium cation with a strong intermolecular negatively charge-assisted hydrogen-bonded acid/conjugate base-pair monoanion. The carboxylic acid H atom is located on an inversion center, while the N atom of the ammonium cation is located on a twofold rotation axis. In the crystal, the N—H bonds of each ammonium cation act as donors with carboxylate O-atom acceptors to form chains along thea-axis direction. The chains are linked by offset π–π interactions [intercentroid distances = 3.588 (2) and 3.686 (2) Å], forming layers parallel to theabplane.
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N-benzylcinchonidinium bromide, C26H29N2O+·Br−, with the systematic name (R)-[(2S,4S,5R)-1-benzyl-5-ethenyl-1-azoniabicyclo[2.2.2]octan-2-yl](quinolin-4-yl)methanol bromide, is a quaternary ammonium salt of the cinchona alkaloid... more
N-benzylcinchonidinium bromide, C26H29N2O+·Br−, with the systematic name (R)-[(2S,4S,5R)-1-benzyl-5-ethenyl-1-azoniabicyclo[2.2.2]octan-2-yl](quinolin-4-yl)methanol bromide, is a quaternary ammonium salt of the cinchona alkaloid cinchonidine. This salt is widely used as a chiral phase-transfer catalyst and chiral resolution agent. Both classical and non-classical hydrogen-bonding interactions, as well as anion effects have been shown to play key mechanistic roles in the catalysis of cinchona alkaloids. In an effort to understand the effects of water on these intermolecular interactions, the structures of anhydrous N-benzylcinchonidinium bromide, (I), and the sesquihydrate, C26H29N2O+·Br−·1.5H2O, (II), were determined.
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X-ray structural determinations and computational studies were used to investigate halogen interactions in two halogenated oxindoles. Comparative analyses of the interaction energy and the interaction properties were carried out for... more
X-ray structural determinations and computational studies were used to investigate halogen interactions in two halogenated oxindoles. Comparative analyses of the interaction energy and the interaction properties were carried out for Br···Br, C-H···Br, C-H···O and N-H···O interactions. Employing Møller–Plesset second-order perturbation theory (MP2) and density functional theory (DFT), the basis set superposition error (BSSE) corrected interaction energy (Eint(BSSE)) was determined using a supramolecular approach. The Eint(BSSE) results were compared with interaction energies obtained by Quantum Theory of Atoms in Molecules (QTAIM)-based methods. Reduced Density Gradient (RDG), QTAIM and Natural bond orbital (NBO) calculations provided insight into possible pathways for the intermolecular interactions examined. Comparative analysis employing the electron density at the bond critical points (BCP) and molecular electrostatic potential (MEP) showed that the interaction energies and the r...
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The title compound, C6H4BrNS, crystallizes in the space group P21/n with one complete molecule in the asymmetric unit. The non-H atoms are nearly planar (r.m.s for non-H atoms = 0.071 Å), with the nitrile group oriented antiperiplanar... more
The title compound, C6H4BrNS, crystallizes in the space group P21/n with one complete molecule in the asymmetric unit. The non-H atoms are nearly planar (r.m.s for non-H atoms = 0.071 Å), with the nitrile group oriented antiperiplanar with respect to the thiophene S atom. Intermolecular Type I centrosymmetric Br⋯Br halogen interactions are present at a distance of 3.582 (1) Å and with a C—Br⋯Br angle of 140.7 (1)°. Additional weaker C—H⋯N, C—H⋯S, and S⋯π interactions are also present. A Hirshfeld analysis indicates Br⋯Br interactions comprise only 1.9% of all the interatomic contacts.
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A new series of π-conjugated oligomers based on the 4,4 dihexyl-4-cyclopenta[2,1-:3,4-']dithiophene vinylene repeating unit has been prepared and characterized by X-ray, electrochemical, spectroscopic (UV-Vis absorption, emission and... more
A new series of π-conjugated oligomers based on the 4,4 dihexyl-4-cyclopenta[2,1-:3,4-']dithiophene vinylene repeating unit has been prepared and characterized by X-ray, electrochemical, spectroscopic (UV-Vis absorption, emission and Raman) and density functional theory methods. The oligomers in their neutral, oxidized and reduced forms have been investigated. The neutral compounds show a longer mean conjugation length than oligothiophenes and oligothiophene-vinylenes and display very rich redox chemistry with the stabilization of polycationic states of which the radical cations and dications are strong NIR absorbers, the latter displaying singlet diradicaloid character. An interesting complementarity between the sequence of aromatic-quinoidal structural segments in the radical cations and dications has been described and interpreted. Two derivatives with the 4,4 dihexyl-4-cyclopenta[2,1-:3,4-']dithiophene vinylene unit, disubstituted either with electron donor, bis(triaryl ...
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The title molecular salt, C14H24N+·C4HO4−[systematic name:N,N-dibutylbenzenaminium 2-hydroxy-3,4-dioxocyclobut-1-en-1-olate], is composed of a protonatedN,N-dibutylaniline cation with a hydrogen squarate monoanion (common names). The... more
The title molecular salt, C14H24N+·C4HO4−[systematic name:N,N-dibutylbenzenaminium 2-hydroxy-3,4-dioxocyclobut-1-en-1-olate], is composed of a protonatedN,N-dibutylaniline cation with a hydrogen squarate monoanion (common names). The disparate bond lengths within the squarate anion suggest delocalization of the negative charge over only part of the squarate moiety. In the crystal, the squarate anions are linked by pairs of O—H...O hydrogen bonds, forming inversion dimers with anR22(10) ring motif. The dimers are linked to the cations on either side by N—H...O hydrogen bonds, and weak C—H...O hydrogen bonds. These cation–anion–anion–cation units are linked by further C—H...O hydrogen bonds, forming layers parallel to (102).
The title molecular salt, C14H24N+·C4HO4−[systematic name:N,N-dibutylbenzenaminium 2-hydroxy-3,4-dioxocyclobut-1-en-1-olate], is composed of a protonatedN,N-dibutylaniline cation with a hydrogen squarate monoanion (common names). The... more
The title molecular salt, C14H24N+·C4HO4−[systematic name:N,N-dibutylbenzenaminium 2-hydroxy-3,4-dioxocyclobut-1-en-1-olate], is composed of a protonatedN,N-dibutylaniline cation with a hydrogen squarate monoanion (common names). The disparate bond lengths within the squarate anion suggest delocalization of the negative charge over only part of the squarate moiety. In the crystal, the squarate anions are linked by pairs of O—H...O hydrogen bonds, forming inversion dimers with anR22(10) ring motif. The dimers are linked to the cations on either side by N—H...O hydrogen bonds, and weak C—H...O hydrogen bonds. These cation–anion–anion–cation units are linked by further C—H...O hydrogen bonds, forming layers parallel to (102).
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The title compound, [Mo(C5H5)(C2H3O)(C24H27P)(CO)2], was prepared by reaction of [Mo(C5H5)(CO)3(CH3)] with tris(3,5-dimethylphenyl)phosphane. The complex exhibits a four-legged piano-stool geometry with trans-disposed acetyl and phosphane... more
The title compound, [Mo(C5H5)(C2H3O)(C24H27P)(CO)2], was prepared by
reaction of [Mo(C5H5)(CO)3(CH3)] with tris(3,5-dimethylphenyl)phosphane.
The complex exhibits a four-legged piano-stool geometry with trans-disposed
acetyl and phosphane ligands. The molecular geometry is nearly identical to that
of the triphenylphosphane derivative, but introduction of methyl groups on the
aromatic phosphane substituents significantly impacts supramolecular organization.
In the crystal, non-classical C—H...O interactions involving the acetyl
carbonyl group lead to a chain motif along [010], and another set of C—H...O
close contacts join inversion-related molecules.
reaction of [Mo(C5H5)(CO)3(CH3)] with tris(3,5-dimethylphenyl)phosphane.
The complex exhibits a four-legged piano-stool geometry with trans-disposed
acetyl and phosphane ligands. The molecular geometry is nearly identical to that
of the triphenylphosphane derivative, but introduction of methyl groups on the
aromatic phosphane substituents significantly impacts supramolecular organization.
In the crystal, non-classical C—H...O interactions involving the acetyl
carbonyl group lead to a chain motif along [010], and another set of C—H...O
close contacts join inversion-related molecules.
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A bis(phosphine)/triflatosilyl pincer-type Rh(i) complex can reversibly store one equivalent of H2 across the Si-Rh bond upon triflate migration from silicon to rhodium. The triflatosilyl complex serves as an effective precatalyst for... more
A bis(phosphine)/triflatosilyl pincer-type Rh(i) complex can reversibly store one equivalent of H2 across the Si-Rh bond upon triflate migration from silicon to rhodium. The triflatosilyl complex serves as an effective precatalyst for norbornene hydrogenation, but Si-OTf bond cleavage is not implicated in the major catalytic pathway. The combined findings suggest possible strategies for M/Si cooperation in catalytic processes.